Menstrual Cycle Noadswood Science, 2016

Menstrual Cycle To explain and describe the menstrual cycle Monday, May 21, 2018 Menstrual Cycle To explain and describe the menstrual cycle

Precise Learning Students should be able to describe the roles of hormones in human reproduction, including the menstrual cycle During puberty reproductive hormones cause secondary sex characteristics to develop Oestrogen is the main female reproductive hormone produced in the ovary. At puberty eggs begin to mature and one is released approximately every 28 days. This is called ovulation Testosterone is the main male reproductive hormone produced by the testes and it stimulates sperm production Several hormones are involved in the menstrual cycle of a woman. Follicle stimulating hormone (FSH) causes maturation of an egg in the ovary. Luteinising hormone (LH) stimulates the release of the egg. Oestrogen and progesterone are involved in maintaining the uterus lining Students should be able to explain the interactions of FSH, oestrogen, LH and progesterone, in the control of the menstrual cycle (higher tier only) Students should be able to extract and interpret data from graphs showing hormone levels during the menstrual cycle (higher tier only)

Hormones Hormones are chemicals secreted by glands in the body Different hormones affect different target organs, with the bloodstream transporting hormones from the glands to the target organs…

Hormones Gland Hormone Target Organs Effect Adrenal gland Adrenalin Liver & heart Prepares body (“flight or fight”) Ovary Oestrogen Ovaries, uterus, pituitary gland Controls puberty and the menstrual cycle in females; stimulates production of LH and suppresses the production of FSH in the pituitary gland Progesterone Uterus Maintains the lining of the womb - suppresses FSH production in the pituitary gland Pancreas Insulin Liver Controls blood sugar levels Pituitary gland Anti-diuretic hormone (ADH) Kidney Controls blood water level by triggering uptake of water in kidneys Luteinising hormone (LH) Ovaries Triggers egg release and progesterone production in ovaries follicle stimulating hormone (FSH) Triggers egg ripening and oestrogen production in ovaries Testes Testosterone Male reproductive organs Controls puberty in males

Puberty At puberty the body starts releasing sex hormones that trigger off secondary sexual characteristics (facial hair in men / breasts in women etc…) and causing egg maturation in women In men the main reproductive hormone is testosterone (produced by the testes) In women the main reproductive hormone is oestrogen (produced by the ovaries)

Menstrual Cycle The menstrual cycle in women is a recurring process in which the lining of the uterus (womb) is prepared for pregnancy, and if pregnancy does not happen, the lining is shed at menstruation Several hormones control this cycle, which includes controlling the release of an egg each month from an ovary, and changing the thickness of the uterus lining These hormones are secreted by the ovaries and pituitary gland

Menstrual Cycle The menstrual cycle begins at day 1, when bleeding from the vagina begins. This is caused by the loss of the uterus lining (with some blood) - this is known as menstruation, or having a period (lasting 3-7 days) By around day 5 menstruation stops. The lining of the uterus begins to re-grow, and an egg cell starts to mature in one of the ovaries Around day 14 the mature egg cell is released from the ovary. This is called ovulation - the egg cell travels down the oviduct towards the uterus

Menstrual Cycle If the egg cell does not meet with a sperm cell (no fertilisation) then the lining of the uterus begins to break down again, and the cycle repeats BUT - if the egg cell meets and joins with a sperm cell (fertilisation) then it attaches to the lining of the uterus and the female becomes pregnant - at this point the cycle stops

Menstrual Cycle Day 1 - menstrual cycle and menstruation (period) begins (lasts 3-7 days) Day 3-7 - menstruation (period) stops Day 14 - an egg cell is released from one of the ovaries (ovulation) Day 28 - if the egg has not been fertilised (by a sperm), the cycle repeats

Menstrual Cycle Complete the menstrual cycle worksheet, sticking all the sections into your book

Menstrual Cycle Menstruation (period) Uterus lining breaks apart without progesterone Most fertile time The egg cell is swept along the oviduct towards the uterus Egg maturation FSH released – egg cell starts to mature in ovary and the uterus lining builds up Ovulation The egg cell is released from the ovary – caused by LH If an egg is fertilised between days 15-28, the menstrual cycle will stop Fertile means the female has the ability to become pregnant (greatest chance of conception) Probably ~ 28 days later: 4th December (although this can be a few days before / after)

FSH The hormone FSH (follicle stimulating hormone) is secreted by the pituitary gland FSH makes two things happen: - It causes an egg to mature in an ovary It stimulates the ovaries to release the hormone oestrogen

Oestrogen The hormone oestrogen is secreted by the ovaries Oestrogen makes two things happen: - It stops FSH being produced - so that only one egg matures in a cycle It stimulates the pituitary gland to release the hormone LH

LH The hormone LH (luteinising hormone) causes the mature egg to be released from the ovary Knowing when LH has surged can be useful when trying to conceive as this informs you of when ovulation has occurred

Progesterone Progesterone is secreted by ovaries, maintaining the lining of the uterus (levels stay high during pregnancy)

Menstrual Cycle

Hormone Interaction The levels of the four hormones fluctuate throughout the cycle and interact with each other to promote or inhibit the release of other hormones… Higher Tier

Practice Questions What effect does FSH have on an egg in the menstrual cycle? What is the function of LH? The graph show the level of a hormone measured in the bloodstream of a woman during her 28 day menstrual cycle Which hormone is shown on the graph and where is this hormone produced?

Answers What effect does FSH have on an egg in the menstrual cycle – it causes and egg to mature What is the function of LH – stimulates the release of an egg (14) The graph show the level of a hormone measured in the bloodstream of a woman during her 28 day menstrual cycle Which hormone is shown on the graph and where is this hormone produced – LH (stimulates the egg) and is produced in the pituitary gland